Quantitative Corrosion Monitoring Using Wireless Electromechanical Impedance Measurements

This article presents an experimental study for wireless monitoring of corrosion damage that might frequently occur in metallic structures. A simple beam structure made from an aluminum alloy was selected for corrosion-monitoring testing and a small lead-zirconate-titanate (PZT) patch-type sensor was surface-mounted to the structure. To obtain an electromechanical impedance data at the PZT sensor, a wireless impedance sensor node that consists of a miniaturized impedance-measuring chip, a microprocessor, and a radio frequency (RF) telemetry was employed. Three different corrosion cases with a different corroded area were artificially inflicted on the beam structure using hydrochloric (HCI) acid, and the electromechanical impedance data were collected in sequence from the wireless impedance sensor node. To quantify the corroded area, the variations of the resonant frequency that represents structural dynamic information were continuously tracked during all the damage cases. Conclusively, it has been found that the amount of the resonant frequency shift got increased when the corroded area got increased. The above experimental results verified that the proposed approach using the amount of resonant frequency shift at the measured electromechanical impedance can be effectively utilized for quantitative analysis of the corroded area in metallic structures.